The Wonder Fumaroles are fissures in the Earth's crust that spew steam and volcanic gas. Scientists measured the temperature of the steam jetting from Big Boiler, the largest fumarole in California's Lassen Volcanic National Park, at 322°F, making it one of the hottest vents in the world.

The Way Start at Lassen's Bumpass Hell parking area, 2.5 hours northeast of Sacramento. From the trailhead, you'll climb 500 feet in the first mile, then descend .5 mile into the most thermally active area in the park. Big Boiler is easy to spot with its steam plume rising 30 feet skyward. You'll catch the smell of rotten eggs, too–that's hydrogen sulfide, a gas released by the magma below. Burbling mud pots and bright yellow crystalline sulfur deposits line the trail. nps.gov/lavo

The Wonder Grizzly bears once roamed all of the North American continent. Habitat destruction and direct conflict with humans have reduced their range by 99 percent in the Lower 48. The rugged backcountry of Glacier National Park forms one of the only large tracts of secure grizzly habitat south of Canada, and it contains the highest population of grizzlies in the contiguous U.S. A report from the U.S. Geological Survey estimates that at least 241 grizzlies live in or around Glacier. That's one griz for every 12 square miles.

The Way Drive up Many Glacier Road to the Iceberg Lake trailhead at the west end of the Swiftcurrent Motor Inn parking lot to access the Iceberg Lake Trail. Glacier's backcountry rangers say this 5.2-mile out-and-back is the best dayhike for grizzly-spotting. Bring 8x binoculars to glass the open meadows and go in the early morning or early evening, when the big bruins forage for berries and grasses. Make plenty of noise (clap your hands or sing) when you pass through densely forested areas and tight switchbacks. nps.gov/glac

The Wonder The Venus flytrap is known all over the world, but it grows natively in the U.S. only in the Carolinas. The infamous plant demands a moist, sandy, acidic, and nutrient-poor soil–and plenty of flies, all of which exist in abundance in the Green Swamp Preserve outside of Wilmington, North Carolina. The flytrap is a leaf modified into a hinged trap with trigger hairs. When insects engage the hairs, the trap snaps shut. Enzymes digest the prey in three to five days, after which the trap gradually reopens.

The Way The Green Swamp Preserve is 5.5 miles north of Supply on NC 211. Take the Green Swamp Preserve Trail, a three-mile out-and-back. Look for flytraps in moist, sun-dappled areas between the grassy savannah and the dense shrubs. Don't be afraid to get down on your hands and knees, as flytraps stand only inches tall. northcarolinaoutdoors.com